1. Field
Embodiments of the present invention describe a method a manufacturing a high quality low dislocation density Group III-Nitride layer at a high growth rate by HVPE on a patterned substrate.
2. Discussion of Related Art
Group III-Nitride semiconductors are finding greater importance in the development and fabrication of the variety of semiconductor devices, such as light emitting diodes (LEDs), laser diodes (LDs) and electronic devices, such as high electron mobility transistors (HEMTs), hetero junction bipolar transistors (HBTs). An important requirement in forming these semiconductor devices is the fabrication of a suitably thick Group III-Nitride layer, such as a gallium nitride layer (GaN), with a smooth surface and a low dislocation density.
Presently Group III-Nitride layers are formed by metal organic chemical vapor deposition (MOCVD) techniques. The use of Group III-Nitrides in many applications has been limited by very high dislocation densities usually in the range of 109-1011 cm−2. Those dislocations formed due to the use of lattice mismatched substrates, such as sapphire. The use of epitaxial lateral over growth (ELOG) has been used to reduce dislocation densities for gallium nitride (GaN) layers grown by MOCVD techniques. This technique, however, at best, provides dislocation densities in the range of 108-9 cm−2. Only over the narrow window regions lower dislocation densities ˜106 cm−2 could be utilized. It has also been proposed to use patterned sapphire substrates (PSS) and ELOG to improve the quality of the grown gallium nitride layer by MOCVD. This combination although an improvement, still has not provided highest crystalline quality films. This combination has provided reported values of full-width-half maximum (FWHM) of double crystal X-ray diffraction (DCXRD) in the (002) and the (102) crystalline planes of 210 arcsec and 240 arcsec, respectively. FWHM is a know technique for monitoring crystalline quality.